The present invention generally relates to the field of integrated circuits, and in particular to robust substrate-based micromachined devices.
As known in the art, micro-fabrication processes are utilized to construct miniature devices that can be batch fabricated at a relatively low cost. In this regard, multiple devices are typically manufactured on a single wafer during micro-fabrication. Well known micro-fabrication techniques are used to form similar components of the multiple devices during the same manufacturing steps. Once the multiple devices have been formed, they can be separated into individual devices. Examples of micro-fabrication techniques that allow the batch fabrication of multiple devices include, but are not limited to, sputtering, evaporation, etching, electroforming (e.g., electroplating, electrowinning, electrodeposition, etc.), packaging techniques (e.g., lamination, screen printing, etc.), photolithography, and thick or thin film fabrication techniques. Since a large number of devices can be formed by the same micro-fabrication steps, the cost of producing a large number of devices through microfabrication techniques is less than the cost of serially producing the devices through other conventional techniques. It is therefore desirable, in many applications, to fabricate devices through micro-fabrication techniques.
Micro-machining is a new technology used to realize microstructures by exploiting common micro-fabrication techniques, e.g., integrated circuit processing technologies. Various microstructures (in particular, miniaturized sensors and actuators) have been realized using this technology; for example, accelerometers, pressure sensors, air flow sensors, micromotors, and micropumps. Since the root of micro-machining technology is in integrated circuit processing technology, micro-machined devices have been primarily realized using silicon substrates. In many applications, the use of traditional silicon-substrate in micro-machined devices may be limited. One limitation for example, is the lack of ability of a surrounding silicon substrate to absorb large mechanical shocks and forces in a harsh environment. Another limitation is the difficulty is interfacing silicon electronics to micro-machined devices using packaging techniques. Thus, heretofore unaddressed needs exists in the industry to address the aforementioned deficiencies and inadequacies.
As will be explained more fully hereinafter, the present invention is the application of robust substrates for both bulk and surface micromachined structures, as well as forming essential structural components of the device package on the robust substrates.
In particular, the use of robust substrates in the surface micro-machined structures described herein is unique in that it combines (1) the use of micro-machining technology (such as film deposition and etching, substrate etching, electroplating, lithography, etc.); (2) the use of electronic packaging technologies (such as screen printing, lamination, chip assembly, etc.); and (3) the use of conventional machining techniques (e.g., drilling, polishing, etc.) to create a new class of micro-machined structures.
These new structures have numerous advantages including low cost, large area fabrication, co-fabrication of micro-machined devices and their packages, and incorporation of new materials into micro-machined systems. Furthermore, structures that are impractical to fabricate using solely traditional micro-machining techniques are now possible.
To maintain robustness, in a preferred embodiment of the invention, metal micro-machined devices use metal shim stock and electroplating technology to fabricate the devices. Many metal shim stocks with appropriate thickness can be good candidates for robust-substrate-based micro-machining.
As mentioned above, one of the advantages of the use of a robust substrate is the possibility of the co-fabrication of a package and micro-machined device using the robust substrate as both a substrate and package.
Another advantage is the robustness of the robust substrate based micro-machined devices. These robust micro-machined devices have the potential to be used in mechanically harsh environments.
In an alternative embodiment, a sensor is fabricated using the robust substrate. The robust substrate based pressure sensor is fabricated using micro-machining technology in combination with conventional machining. In particular, a robust substrate based pressure sensor is fabricated using stainless steel as a substrate, Kapton(trademark) polyimide film as a pressure-sensitive diaphragm, and electroplated nickel as a back electrode.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.